John O'Boyle/Star-LedgerJeff DeWeese, managing partner of Grease Lightning, a company that recycles used cooking oil to be converted to biodiesel. Behind him, red tanks hold oil at various stages of processing.

Anyone who has ever deep fried the occasional chicken has probably wondered what to do with the cooking oil.

You can’t cool it, refrigerate it and reuse it indefinitely. Pouring it down the drain causes problems in the pipes and compromises the water supply. And for some, it would be an offense to throw out a container-full knowing it will end up in a landfill.

The best place to discard the used oil could be the nearest restaurant.

An increasing number of eateries are being paid as much as 50 cents a gallon to recycle oil that once cooked french fries, mozzarella sticks and chicken nuggets. That means more than a few would accept used oil from home cooks just as some mechanics take used motor oil.

In large quantities, used vegetable oils such as soy, peanut and canola have become a commodity. They can be processed into fuel that runs school buses and heats homes. Known as biofuels, they can even generate electricity. Grease is now in demand, and several companies have been sucking it up for resale.

Among them is Grease Lightning, a 2-year-old company whose major clients include the Prudential Center in Newark and the Eataly Italian food complex in Manhattan. With a crew of 40 employees and 12 trucks between its facilities in Newark and Hicksville, N.Y., Grease Lightning recycles more than 7 million gallons of grease a year from some 3,000 restaurants and fast food chains in New Jersey and New York, according to company officials. It also has partnerships with municipalities such as Jersey City, Newark and Hoboken to encourage grease recycling.

At the company’s Newark plant, a line of red 20,000-gallon tanks is tented by a steel-framed fabric building. They brim with dark oil at various stages in the process the company uses to refine it for biodiesel, an alternative to standard petroleum diesel.

View full sizeUntreated grease (left) must be evaporated and filtered before it can be sold for conversion into biofuel, an alternative to standard diesel fuel.

“When we get it, it’s in a very raw state,” says Jeff DeWeese, a managing partner. “We bring it here and we go through the recycling process.” Basically, that entails removing water and solids. The oil is heated to burn off moisture, spun in a massive centrifuge to isolate the solids and then strained through very fine filters. Nothing goes to waste, DeWeese says — even the solids are composted.

Recycling used kitchen oil still has all the patriotic potential of the World War II Fat Salvage Campaign, but instead of being culled for glycerine in wartime, today’s grease gathering produces cleaner-burning fuel, encouraging feel-good fat recycling in the age of global warming. Biodiesel is also American-made, touted as helping to reduce the nation’s dependence on imported fossil fuel. And as long as there’s a mass appetite for doughnuts and fries, grease is a renewable energy source that’s in constant supply.

While most biodiesel is now mixed with traditional fuels such as home heating oil or standard diesel, DeWeese says he has been running the turbo diesel engine of his 2011 Volkswagen Jetta on 100 percent biodiesel for about two years without trouble.

“I opt to practice what I preach,” he says. Biodiesel can fuel existing diesel engines without modifications, he explains. “It’s very comparable to diesel.“ DeWeese, an engineer who previously developed biodiesel technologies, isn’t only experimenting with his car. His company hopes to patent a process that reduces the time and increases the efficiency of grease refining. In the meantime, the company’s Manhattan-based marketing arm is working to sign on more eateries where deep-fried delights are a big part of the bottom line.

Greg Reinert, a spokesman for the New Jersey Board of Public Utilities, says a work group is looking at how biodiesel and other alternative fuels can be part of the state's Energy Master Plan.

“It may have a role in terms of the role different alternative fuels can play in the state’s energy mix,” he said. “Biodiesel can also be used for energy generation. That’s something that’s still being evaluated along with other technologies.” DeWeese has a vision that someday there will be receptacles where anyone can recycle grease.

At least one of his competitors has made that possible in Maplewood. There, residents can pour out used oil at the Department of Public Works facility to be collected by Darling International, a Texas rendering and fat-recycling company with offices in Newark.

Hazardous-waste collection facilities in several counties (search earth911.com for sites) also will accept cooking oil, which can be safely composted and is not really hazardous waste. But citing the health hazards of deep frying, one Burlington County staffer suggested oven “frying” when asked where to recycle grease. That would be a better dietary option, she said — and eliminate the need to get rid of so much grease.